Multiple switch actuator



Feb. 22, 1944. NEWTON 2,342,615

MULTIPLE SWITCH ACTUATOR Filed Jan. 7, 1942 2 Sheets-Sheet 1 I INVENTOR. Alwim. '13. Newlam Feb. 22, 1944. A B, N WT 2,342,615 I MULTIPLE SWITCH ACTUATOR Filed Jan. 7, 1942 2 Sheets-Sheet 2 Fin-3,. 2.

IN'VENTOR. Alwiru 'B. N'cw-l-om Patented Feb. 22, 1944 MULTIPLE SWITCH ACTUATOR Alwin B. Newton, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application January 7, 1942, Serial No. 425,888 19 Claims. (oi. 200 s1.5)

The present invention is concerned with automatic controls wherein a plurality of switches, for instance, switches controlling poly-phase electrical circuits are to be actuated simultaneously.

The primary object of my invention is to provide means for simultaneously moving a plurality of switches or like devices from one position to another.

Another object of my invention is to provide an arrangement for simultaneously moving a plurality of switches from a first position to a second position wherein separate adjustments are provided for the points at which the switches are actuated from each position to the other; that is, if the switches are actuated automatically in response to a variable condition, the arrangement provides for independently adjusting the value of the condition at which the switches are moved from each position to the other.

Another object of the invention is to provide a control mechanism comprising an actuating member for actuating a plurality of devices, the actuating member being movable by snap acting mechanism.

Another object of the invention is to provide an actuating mechanism for automatic controls comprising a whifiletree type of lever, both ends of which are movable with a snap action.

Another object of the invention is to provide an actuating mechanism for a plurality of switches or the like comprising an actuator member for the switches, the member being movable with a snap action by means of a whiiiletree type of lever having at least one end movable with a snap action.

My invention finds one application in controlling poly-phase circuits in systems wherein a poly-phase motor is used as a prime mover, for instance, the motor for driving the compressor of a mechanical refrigeration system as shown in the drawing. It is, of course, desirable that all the wires of the poly-phase circuit have their controlling switches opened and closed simultaneously. As pointed out above, it is the object of my invention to provide means for simultaneously opening and closing the various circuits.

In the drawings:

Figure 1 is a diagrammatic view partly in detail of one form of my multiple switch actuator.

Figure 2 is a modified form of my multiple switch actuator with a side of the casing removed so as to better illustrate the device.

In the drawing, numeral designates generally a mechanical refrigeration system comprising a three-phase electrical motor H which drives a refrigerant compressor I2 through a belt i3. The compressor is connected to a condenser H by a pipe l5 and the compressor is connected to an evaporator i6 by a pipe 11. The suction side of the compressor is connected to the evaporator by a pipe l8. Interposed in the pipe 11 leading to the evaporator is an expansion valve 20 which is of the superheat type adapted to maintain a constant degree of superheat at the outlet of the evaporator. The expansion valve 20 is of a wellknown type, the operating mechanism including an expansible and contractible chamber which is connected to a thermal bulb 2| by means of a capillary'tube 22, the thermal bulb being disposed in intimate heat exchange relationship with the pipe through which refrigerant is discharged from the evaporator so that the volatile liquid in the thermal bulb vaporizes and developes a pressure depending upon the temperature of the refrigerant leaving the evaporator.

The motor H is a three-phase motor and the three-phase circuit is comprised of wires 25, 26 and 21 which lead to respective switches 28, 29 and 30 located within a control device 3|. One

" of the terminals of each of the switches is also connected to the wires 32, 33 and 34, respectively.

The construction and arrangement of the controller 3i constitutes the principal part of my invention. Each 01; the switches 28, 29 and 30 comprises a housing which may be made of Bakelite or the like and the switches are preferably of a snap acting normally open type. A preferred form of switch is shown in Patent Number 2,318,734, issued May 11, 1943. The switches are operated by plungers 35, 36 and 31, respectively, which close their respective switches when the plungers are pushed inwardly, the plungers moving outwardly causing the switches to open whenever the plungers are released. Obviously a given amount of inward movement must be imparted to each of the plungers to cause closure of their respective switches, and upon release of the plungers they will move outwardly a corresponding amount to open the switches.

All of the plungers engage in abutting relation with adjusting screws carried by a lever member 4| having an ear 42 pivoted to a bracket 43'. By rotating the lever member 4! in a counter-clockwise direction the plungers are moved inwardly, and upon rotating the lever member M in a clockwise direction the plungers are permitted to move outwardly. By adjusting the screws the snapping points of'the switches with respect to F lever'll can be nicely adjusted so that whenever the lever is in a position to snap any one switch it is in a position to snap them all.

At the left end of the lever 41 there is secured a flexible bracket 44, part of which is spaced from the end of member 4!, there being a screw 45 extending through the bracket 44 and member 4| for purposes which will presently be described.

Numeral 55 designates a lever of the whithetree type having a downwardly extending projection M at its mid point which engages in abuttingrelationship the bracket 44. The left end of the member d has an aperture 48 through which extends a stop pin 49 and the right end of the member 45 has an aperture 50 through which extends a stop pin 5|. Numeral 52 designates a coil tension spring, the lower end of which is attached to an extending portion 53 at the left end of member 45, th upper end of the spring being attached to a member 54 which is engaged in screw-threaded relationship by an adjusting screw 55 which extends through a sidewall of the casing 3i, the purpose of the screw 55 being to adjust the tension of spring 52. Numerals 56 and 51 designate toggle members, one end of each of which is engaged in a recess inthe portion 53 of member it. The other endof toggle member 5'! engages a similar recess in a fixed abutment and the other end of toggle member 56v engages a recess formed in a resilient bracket member 58 suitably mounted within the casing of the, controller 3!. From the construction so far described, it is obvious that the toggle members 56 and 5? and the spring 52 are operable to impart snap action to the left end of the whifiletree member d5. The spring rate of the toggle mechanism with'respect to the spring rate of spring 52- i such'that once the end of lever 45 starts to move, the movement will be with a snap. The upward force exerted by the toggle mechanism decreases faster than" the force of spring 52 increases when member 45 moves downwardly. Thus the movement is with a snap.

The right end of the member $5 is movable with a snap action in exactly the same manner as the left end, the elements associated with the right end" being identical with those on the left. The elements associated with the right end of, the member 56 therefore bear 'the same reference characters as the corresponding elements on the left end of the member 46 but with the identifying letter a. Further description-of the mechanism at-t-he 'rightendof the lever member this thereforeunnecessary.

*Themechanism for actuating the whiflletree. member 45 comprises an expansible andcontractible member which is preferably a bellows locatedwithin a housing 6.6. The movable. end. of the bellows isattached to a stem 65 which engages the mid point of the member 45 so. as to move-the member in a downward directionwhen the bellows. expandsandto permit it to move upwardly under the. influence of the tension springs when the bellows-contracts. The interior ofthe bellows is connected to the pipe I8 by a tube 65 so that the bellows expands and contracts in, accordance with thesuction p essure of the refrigeration system. V 1

At the right end of the lever member 4| is a bracket Ma, corresponding to the bracket 44 except that it is not flexible having a screw 45a.

extending through it, this screw corresponding to the screw G5. Associated with the rightv end,

of the lever member 4! is a whifiletree which is the same .as and corresponds to. the whillletree 45,.its ends havingsnap; actin m chanism 3-55 ciated therewith, the same as the snap acting mechanism already described. Inasmuch as the details of the mechanism associated with the right end of lever member A! are the same as those of the mechanism at the left end, the details at the right end bear the same reference characters with the identifying letters a, b and c. The bellows which actuates the lever 46a is connected to the pipe !5 by a capillary tube 6'1 so that the bellows expands and contracts in accordance with the discharge pressure of the compressor i2.

With the parts in the position shown, the projection Ala is spaced from bracket 44a, and as will presently be described, it does not engage the bracket Mia, for actuating the lever ll except in the event of an unduly high discharge or head pressure.

With reference to the operation, the springs 52 and 52b are normally adjusted so as to be under a greater tension than the springs 52a and 520 respectively. With the parts in the position shown, the switches 28, 29 and 30 are open and the refrigerating system is not in operation so that the suction pressure is rising. As the suction pressure rises, the bellows within housing 64 expands, and inasmuch as the spring 52a is adjusted so as to have less tension than the spring 52, the right end of member 45 moves downwardly as the bellows expands. The right end of member to is. moved downwardly with av snap action as described above until the pin 51 engages the upper side of aperture 55. This occurs at a predetermined suction pressure determined by the adjustment of screw 55a. This movement of the right end. of member 46 is of course imparted to the lever A l, the lever 4| being moved correspondingly in a counter-clockwise direction, the plungers 35, 35 and 3'! being moved inwardly a predetermined amount but not enough to close the switches 28, 29 and 35'. As the suction pressure continues torise, expansion of the, bellows within housing 6'4 will now cause the left end of member 56 to be moved downwardly, and the left end of member 35 will be snapped downwardly until the pin 29 engages the upper side of aperture 48, this occurring at'a predetermined suction pressure which isv dependent on the-setting of screw 55. This snap movement of member 46 will likewise be imparted to the lever member t! which will be again snapped in a counterclockwise direction and the plungers 55, 35 and 31 will of course be snapped inwardly simultaneously and this time an amount great enough to simultaneously close the switches 28, 25! and 35. Closure of the switches will put the motor I l in operation and the refrigeration system Will operate to produce refrigeration.

By adjusting the screw 45 the relationship between the whifiietree member at and the lever ll may be adjusted. v

As the refrigeration system operates, the suction pressure will fall, and as it falls the bellows within housing 64' will contract. The left end of member 565 will now move upwardly first inasmuch as, spring 52- is under greater tension than spring 52a, and the left end of member 4B will be snapped upwardly to the position to-which it is shown in the drawings. Thisrnovement will of course be imparted to thelever; H which will'be correspondingly snapped in a clockwise direction so as to release the plungers 35,35 and 3'1: soas to let them moveoutwardly a; givenamount but not enough to open theirrespective switches. Asthe suction pressure continuesto fall and the;

bellows'within housing 64 continues to contract; the right end of member 46 will now move upwardly under the influence of spring 52a, and the right end of member 46 will be snapped upwardly until the stop pin engages the lower side of aperture 56, as shown on the drawing. This snap movement will of course be transmitted to the lever member 4| which willbe snapped a corresponding amount in a clockwise direction, relieving the pressure on the plungers 35, 36 and 31 and allowing them to simultaneously move outwardly to positions wherein their respective switches are opened.

From the foregoing, it can be seen that the switches 28, 29 and 30 are simultaneously actuated to their closed and open positions under the influence of the lever member 4|. The suction pressure at which the switches areclosed is determined independently by the adjustment of screw 55 which adjusts the tension of spring 52, this being true because sprin 52 controls the snapping of the left end of member 45. The suction pressure at which the switches are opened is independently controlled by the adjustment of screw 55a which adjusts the tension of spring 52a, this being true because the tension of spring 52a determines the suction pressure at which the right end of member 46 will be snapped upwardly so as to cause the member 4| to be snapped to a position wherein the switches are opened.

The mechanism associated with the right end of the lever member 4| functions in exactly the same manner as the mechanism at the left end so that the description need not be repeated. The mechanism at the right end of the controller 3| will function to cause opening of the switches in the controller upon the occurrence of an unduly high head or discharge pressure. Stating this operation briefiy, when the head pressure rises to a predetermined value, the right end of member 48a will be snapped downwardly first, the spring 520 having less tension than the spring 52?). At a higher predetermined head pressure, the left end of member 4611 will be snapped downwardly and at this pressure the projection 41a will engage the bracket 44a moving the lever 4| in a clockwise direction to a position wherein the switches 28, 29 and 30 are open. The lever 44 will be held in a position wherein the switches are open until the head pressure decreases to a predetermined value at which both ends of the member 46a have snapped upwardly to the position shown in the drawing.

The bracket 44 provides a strain release device for relieving the strain when both the projections 47 and 41a are engaging their associated brackets; that is, these brackets relieve the strain at times when the suction pressure responsive device is attempting to close the switches when at the same time the head pressure responsive mechanism is holding the lever 4| in open position of the switches.

It will be noted that when the head pressure responsive mechanism has moved lever 4| to open position of the switches the head pressure must fall to a predetermined value at which the ends of lever 46a have snapped upwardly. This is a desirable characteristic.

Referring to Figure 2 of the drawings, I have shown a modified form of my invention, this form of the invention also employing a floating lever through which the switches are actuated, the floating lever being operated in a somewhat different manner in this form of the invention. In Figure 2 numeral '10 designates a generally rec-- switches H and 12 are located. There may be two or more switches in the casing and the switches are of the same type as in the previous modifications. In the present modification the operating stems of the switches are designated by the numeral 73.

The actuating mechanism for the switches comprises a floating lever 16, which is actuated by an expansible and contractible bellows device within a housing 11, the bellows being connected to the suction side of the refrigeration system as in the previous embodiment by a tube '18. The bellows upon expansion actuates a stem 19 against the force of a spring within the housing, the tension of which may be adjusted by an adjusting screw through which the stem 19 extends. The upper end of the stem 19 is attached to a ball 8| which is loosely disposed in an opening in the lever it. Numeral 82 designates a flexible leaf, the right end of which is attached to the upper side of the lever E5, the leaf normally engaging the ball 8%. Numeral B3 designates a similar leaf attached to the lower side of lever 16 and engaging the ball the stem 19 extending through an openin in the leaf 83. The leaves 82 and 83 and the ball Si form a strain release connection between the stem 19 and the lever 76, the resiliency of the leaves permitting relative movement between the stem is and the lever 16. The right end of lever E8 is movable between fixed stops 84 and 5 and the left end of lever 76 is movable between stops formed by two manually adjustable cams 85 and 87, both of these cams having a gradual rise, that is, a spiral contour and the cam 85 is mounted on a shaft which extends through a side wall of the casing '10 and which is adjustable, that is, rotatable by a manual adjusting knob 88. The cam 87 is similarly adjustable by a knob 39. Adjacent each of the manual adjusting knobs and rotatable therewith is an indicating dial to indicate the position of the respective cams.

At the right end of lever 16 is a downwardly extending bifurcated portion 99 and engaged between the bifurcations is the left end of a pivoted lever pivoted on a pivot 36. The operating stems T3 of the switches abut adjusting screws l4 carried by a broadened portion of the lever 35, these screws serving the same purpose as the corresponding screws of the previous embodiment. The right end of lever 95 engages in a notch in the end of a toggle member 91, the opposite end of which is pointed and which engages in a seat near the end of a resilient spring bracket 98 the lower end of which is attached to a side wall of the casing lil. From the foregoing it can be seen that when the lever 95 is rotated in a clockwise direction the knee formed by the lever 95 and toggle member 91 will tend to straighten out and as it tends to straighten out the parts will move with a snap action toward a position wherein the members 95 and Q7 lie along a straight line.

The operation of the device as so far described is as follows: Upon a rise in suction pressure occurring when the refrigeration system is not in operation the bellows within housing TI is expanded against the force of the spring within the housing thus moving the left end of lever I6 upwardly until it engages the cam 8'8, this of course occurring at a suction pressure which will depend on the adjustment of cam 86. The right end of lever 16 so far remains in engagement with stop 85, then upon further increase in suction tangularhousing or casing within which the snap pressure the right end of lever H5 will begin to move upwardly and as the lever 95 starts to rotate in a clockwise direction in the manner described above, the toggle mechanism will snap to a position wherein the right end of lever 16 is in engagement with stop Be. When the lever 95 is thus snapped the stems of all the switches are snapped upwardly, that is, inwardly to closed position of the respective switches and this of course occurs simultaneously with respect to all of the switches.

It is tobe noted that a characteristic of this arrangement is that little or no operating pressure is applied to the member 13 until the switches are actually actuated. The force produced by the suction pressure is applied mainly against the sprin within housing 11 and against the cam 86.

When the suction pressure falls due to operation of the system, the bellows within housing 1'! will contract moving the left and of lever 16 downwardly until it engages cam 81 and this wil occur at a suction pressur determined by the setting of cam $1. Upon further decrease in suction pressure the right end of lever 16 will be moved downwardly thus moving lever 95 in a counter clockwise direction and causing it, by reason of the toggle mechanism to snap into the position shown in Figure 2. When lever 95 is thus snapped the stem of all the switches will of course be moved downwardly simultaneously with a snap action to open position of the switches.

From the foregoing it is apparent that with the arrangement of Figure 2 the cut-in and cut-out pressures of the switches are determined independently by adjusting the knobs 88 and 89.

Numeral i W designates a second housing similar to housing ll associated with the outside of casing '50. Housing Hi5 contains an expansible and contractible bellows, the interior of which is connected to the high pressure side of the refrigeration system by a tube Hll so that the bellows expands and contracts in accordance with head pressure of the system. The bellows expands in response to head pressure against a spring, the tension of which is adjustable by adjusting nut 552, the bellows actuating a stem I93 which extends through the nut I02, Numeral Hi4 designates a lever pivoted on a pivot I05, the left end of the lever being connected to portion 90 of lever It by link H36 and the right end of the lever being engageable by the stem I93. If the head pressure rises to a predetermined value when member 73' is in closed position of the switches the stem Hi3 will engage lever N34 rotating it in a counterclockwise direction so as to snap the lever 95 to open position of th switches. This will occur even though the suction pressure responsive device haspositioned the lever 16 in a position wherein normally the switches are closed, the strain release connections between stem 19 and lever it permitting downward movement of the right end of lever 76 under these circumstances. If the switches are opened by the head pressure responsive device the head pressure will have to drop somewhat before the switches can be reclosed by the suction pressure responsive device.

The suction pressure device of my invention may operate between fairly widely diilerent pressures, that is, over quite a wide range of presure so that fairly widely differing forces are developed by these pressures. However, by reason or my particular arrangement, these forces which sometimes may be quite large are not im parted to the actuating member 13 of the switches. In practice, the switches may be constructed of relatively small and inexpensive parts and so that only very small forces are required to move the switches from one position to the other. In the embodiment of Fig. 2 the switches may of course be actuated by plungers in the same manner as in Fig. 1,

The embodiments of my invention which I have disclosed herein are representative of its preferred forms. Various other forms and modifications of the invention will occur to those skilled in the art and therefore the disclosure is to be interpreted in an illustrative rather than a limiting sense. The invention is to be limited only in accordance with the claims appended hereto.

I claim as my invention:

1. In apparatus of the character described, in combination, control means including a floating lever, means for limiting the movement of the lever, means for causing said lever to move between first and second positions with a snap action, and means comprising a plurality of control devices actuatable by said lever and adjustment means for regulating the actuation of each of said control devices by said lever.

2. In apparatus of the character described, in combination, control means including a floating lever, means for limiting movement f the lever, means to be controlled operable in response to movement of an intermediate point of the lever, and means for causing each end of the lever to move between first and second positions with a snap action.

3. In apparatus of the character described, in combination, control means comprising a lever, means operable upon an intermediate point of-the lever for moving it, means to be controlled operable in response to movement of an intermediate point of the lever, a plurality of snap acting means associated with an end of the lever to cause said end to move between first and second positions with a plurality of snap actions whereby such snap action is imparted to said means to be controlled.

4. In apparatus of the character described, in combination, control means comprising a floating lever, means operable upon an intermediate point of the lever for moving it, means to be controlled operable in response to movement of an intermediate point of the lever, means associated with the ends of the lever to cause each end to move between first and second positions with a snap action, whereby the snap action is imparted to said means to be controlled.

5. In apparatus of the character described, a control mechanism comprising a floating lever, means whereby each end of the lever is movable between two positions with a snap action, control means arranged to be moved from one posi- ,tion to another by the lever, said control means being in one of its said positions when both ends of the floating lever have been snapped one way, and said control means being in its other position when both ends of the floating lever have been snapped the other Way.

6. In apparatus of the character described, in

combination, a plurality of devices adapted to be snapped between first and second positions, means comprising a control member, means associated with said control member comprising automatic condition responsive snap acting mechanism for causing said control member to simultaneously actuate said devices, said last means being independently adjustable so as to regulate the value or degree of the condition at which the devices are actuated to each position. 7. In apparatus of the character described, in

' combination, a plurality of devices adapted to be snapped between first and second positions, means comprising a control member, means associated with said control member including a floating lever having means arranged to cause each end of the lever to move between two positions with a snap action, means for independently adjusting the snapping of each end of the lever, said lever being so related to said control member that snapping of one end of the lever governs operation of the control devices to the first position and snapping of the other end of the lever governs operation of the control devices to the second position.

8. In apparatus of the character described, in combination, a control device, an actuator for the device, means for moving the device comprising a first condition responsive means arranged to move thedevice between open and closed positions, said moving means being so constructed and arranged as to provide for independently adjusting the values or degrees of the condition at which the device is opened and closed, another means for moving the actuator comprising a second condition responsive means arranged to move the device between open and closed positions, said other means being so constructed and arranged as to provide for independently adjusting the values or degrees of the condition at which the device is opened and closed.

9. In apparatus of the character described, in combination, a control device movable between first and second positions, an actuator for the device, means for moving the device comprising condition responsive mechanism having a floating lever arranged to impart motion to the actuator, means whereby the motion imparted to the actuator is snap movement, adjustable resilient means associated with a first point on said lever and adjustable resilient means associated with a second point on said lever, the parts being so arranged that the adjustment of one resilient means controls the value or degree of the condition at which the device is moved to one position and the adjustment of the other resilient means controls the value or degree of the condition at which the device is moved to the other position, another means for moving the value or degree of the condition at which the V device is moved to the other position by said last lever.

10. In apparatus of the character described, in combination, a switch, switch actuating means comprising a floating lever, means whereby each end of the lever is moved with a snap action, the movement being imparted to the switch, means for independently adjusting the snapping of each end of the lever, said actuating means comprising a second floating lever, means whereby each end of the second lever is moved with a snap action, the movement being imparted to the switch, and means for independently adjusting the snapping of each end of the second lever, the adjustments of the snapping of the floating levers controlling the opening and closing of the switch.

11. In apparatus of the character described, in combination, a control device movable between first and second positions, an actuator for the device, means for moving the device comprising condition responsive mechanism having a floating lever arranged to impart motion to the actuator, means whereby the motion imparted to the actuator is snap movement, ad- J'ustable resilient means associated with a first point on said lever and adjustable resilient means associated with a second point on said lever, the parts being soarranged that the adjustment of one resilient means controls the value or degree of the condition at which the device is moved to one position and the adjustment of the other resilient means controls the value or degree of the condition at which the device is moved to the other position.

12. In apparatus of the character described, in combination, control mechanism comprising a lever arranged to pivot about any one of a plurality of points as fulcrums, pressure responsive mean for moving the lever, means forming stops between which one end of the lever is movable, and sprin toggle snap mechanism associated with the other end of the lever whereby said other end of the lever is snapped from one position to another, the lever upon being actuated by the pressure responsive means engaging one or the other of said stops before tripping the spring toggle mechanism.

13. In apparatus of the character described, in combination, control mechanism comprising a lever arranged to pivot about any one of a plurality of points as fulcrums, pressure responsive means for moving the lever, means forming stops between which one end of the lever is movable, and spring toggle snap mechanism associated with the other end of the lever whereby said other end of the lever is snapped from one position to another, the lever upon being actuated by the pressure responsive means engaging one or the other of said stops before tripping the spring toggle mechanism and at least one of said stops being adjustable to adjust the pressure at which the spring toggle mechanism is tripped.

14. In apparatus of the character described, in combination, control mechanism comprisin a lever arranged to pivot about any one of a plurality of points as fulcrums, pressure responsive means for moving the lever, resilient means resisting said pressure responsive means, means forming stops between which one end of the lever is movable, snap mechanism associated with the other end of the lever whereby said other end of the lever is snapped from one position to another and a plurality of switches actuatable simultaneously by said lever and snap mechanism.

15. In apparatus of the character described, in combination, control mechanism comprising a lever arranged to pivot about any one of a plurality of points as fulcrums, pressure responsive means for moving the lever, resilient means resisting said pressure responsive means, means forming stops between which one end of the lever is movable, snap mechanism associated with the other end of the lever whereby said other end of the lever is snapped from one position to another, a plurality of switches actuatable simultaneously by said lever and snap mechanism; and

- a second pressure responsive means arranged to be operable to move the other end of the lever to open position of the switches.

16. The combination comprising, a plurality of control devices adapted to be actuated between first and second control positions, means comprising a control member, means associated with I said control member comprising automatic condition responsive snap acting mechanism for causing said control member to actuate said control devices, and independent adjustment means so constructed and arranged as to regulate the actuation of each of said control devices by said con-, trol member.

by Said lever.

18. The combination comprising, a control device adapted to be moved between first and sec- 0nd positions, a control member, means associated vice adapted to be moved between closed and open positions under one set of conditions, a control member, means associated with said control member comprising automatic condition responsive snap acting mechanism for causin said control member to actuate said control device in a plurality of snap action steps between said closed and open positions, and a second means associated with said control member comprising automatic condition responsive snap acting mechanism for causing said control member to actuate said control device in a plurality of snap action steps between open and closed positions under a second set of conditions.

ALWIN B. NEWTON. 

